Electric switch.



W. T, PRINGLE.

ELECTRlC SWITCH. APPLICATION FILED JAN. 20. 1915.

Patent-ed an. 8, 1918.

WILLIAM T. PRINGLE, OF WYNCOTE, PENNSYLVANIA.

ELECTRIC SWITCH.

Specification of Letters Patent.

Patented can. 8a., 191 .8.

Application filed January 20, 1915. Serial No. 3,264.

To all whom it may concern:

Be it known that I, WILLIAM T. Panama, a citizen of the United States, residing at VVynco'te, in the county of Montgomery and State of Pennsylvania, have invented a certain new and useful Improvement in Electric Switches, whereof the following is a specification, reference being had to the accompanying (ll'ilYlIl'w My invention is applicable to knife switches and may be employed with particular advantage in connection with such switches wherein the blades are devoid of operating handles. Switches of such simple type are employed in circuits carrying heavy current, where they normally remain closed but are provided so that the circuit may be broken by opening them in case of emergency. However, it is to be llIlClElstood that my invention may be employed in switches of any desired form.

It is now known that,-aside from the mechanical strains, tending to open them, to

which such switches are normally subjected; under abnormal conditions, such as an overload of the circuit in which they are in cluded, such switches are subjected to electrical stressestending to separate the blades from their terminals, so that under such abnormal electrical conditions the switch blades may be automatically thrown open, unless means he provided to positively prevent such abnormal movement. Therefore, it is the object of my invention'to provide means for positively locking a blade of a knife switch in closed position, so constructed and arranged that it cannot be released by any electrical strain to which the switch may be subjected, and cannot be released by any accidental mechanical strain, but requires for its release a predetermined movement of the locking means such as may only be imparted to it intentionally.

As hereinafter described my invention includes the combination with a switch blade and'the terminal with which it is adapted to detachably electrically connect, of a looking spring forming an abutment which normally obstructs the passage of the blade to open position and prevents its opening movement until said spring is moved aside. In the form of my invention hereinafter described the spring. extends transversely to the length of the blade and is so slotted that the end of the blade projects through the spring when the blade is in closed position;

so that the spring must be shifted longitudinally with respect to the blade to free the end of the latter.

My invention includes the various novel features of construction and arrangement hereinafter more definitely specified.

In the drawings; Figure I is a front view of a switclicomprising a single blade and embodying'my invention.

Fig. II is a side elevation of the switch shown in Fig. I.-

Fig. III is a fragmentary side elevation of the switch operating handle indicated in broken lines in Fig. II.

In said figures; l is an insulating base which may be of any suitable form or material, for instance a plane slate slab, which supports theswitch terminals 2 and 3 which are conveniently connected therewith by.

their respective screw threaded shanks 5 and 6 extending through said slab, in engagement with respective electrical conductors of the circuit in which the switch is included. Said shanks are conveniently engaged by the nuts 8 and 9 to hold said ternliigals 2 and 3 in rigid relation with said s a The switch blade 10 is pivoted to said terminal 2, conveniently by the bolt 11, so that it may be turned to and from contact with the switch terminal 3, and when closed in contact with the latter may occupy the position shown in Fig. II, in which position said blade 10 is normally retained by the locking spring 14 which is held stationary at one end between said slab 1 andterniinai. 3 and has the slot 15 through which the end of said switch blade 10 projects, so that said spring extends transversely to the length of said blade. and its unslotted free end 16 forms an abutment which must be displaced in the direction of the length of said blade to release the latter so that it may be opened. Such releasing movement may be effected in any convenient manner, but I .iind it convenient to employ an operating handle 17 having the pin 18 for engagement in the hole 19 in the end of said switch blade 10, and having the cam flange 20 adapted to bear upon the locking spring 14 to shift the latter clear of the blade when said handle is turned from the position shown in dash lines in Fig. II to the position shown in dot and dash lines in said figure. When turned to the latter position; said Handle may be employed toswing the switch,

blade 10 open, by the continued engagement of its pin 18 in said hole 19. Of course, said spring 1 L returns, of its own resiliency, to the position shown in the drawings, when released from engagement with the handle flange 20, by the opening movement of the blade 10, above described.

Although it is not necessary to do so, I

refer to so incline the end-of theswitch blade 10, for instance as shown at 21, that stresses upon said blade tending to open it press said inclined portion of the blade against the abutment end 16 of said spring in such manner as to otter additional resistance to the releasing movement of the SPIH'IY'. I

Said blade 10 may be returned to the closed position shown, without any manipulation of said spring 14; the innercorner of the free end of said blade 10 being rounded as indicated at so as to slide past the oppositely rounded abutment end 16 of the locking spring 1i and automatically reengage the latter,

Although, in applying my invention to the simple type of switch chosen for illustration, I find it convenient to so construct and arrange the locking spring as to engage the end of the sivitch blade; it .is to be understood that other forms and arrangements of my invention may beemployed.

'Tiherefore, I do not desire to limit myself to the precise details of construction and arrangement herein set forth, as it is obvious that various modifications may be therein without departing from the essential features of my invention as defined in the appended claims.

I claim 1. In an electric switch, the combination with insulating base; of two switch terminals mounted. on said base; aswitch blade pivotally connected with one of said terminals and arranged to swing to and from electrical contact with the other-of said terminals; a locking spring having one end held betieen the last named terminal and said base and having its free end extending transversely to the length of said blade, with a slot through which. the free end of said blade projects when in closed position; said locking spring having its unslottcd free end rounded and arranged as an abutment which n rinally obstructs the passage of said blade a open position and prevents its opening increment until said spring is moved aside; said blade havingits portion which cpgages said abutment so inclined that stresses upon said blade tending to open it press said inclined portion thereof against the abutment in such manner as to offer additional resistanee to t e releasing movement of the spring, and the or the free end of said blade being i anged to cooperate with the re 1; said. spring to move the latter aside when said blade is shifted from open. to closed position, and said blade having a hole adjacent said spring, arranged to engage an operating handle; and, an operating handle having a pin adapted to turn in the hole of said blade, and having a cam flange arranged to encounter said spring and release it from said blade by shifting said spring longitudinally with respect to said blade when said handle is turned. i

2. In an electric switch, the combination with an insulating base; of two switch terminals mounted on said base; a switch blade pivotally connected with one of said terminals and arranged to swing to and from electrical contact with the other of said ter minals; a locking spring extending transversely to the length of said blade, with a slot through which the free end of said blade projects when in closed position; said locking spring having its unslotted free end arranged as an abutment which normally obstructs the passage of said blade to open position and prevents its opening movement until said spring is moved aside; said blade having its portion which engages said abutment so shaped that stresses upon said blade tending to open it press said inclined portion thereof against the abutment in such manner as to offer additional resistance to the releasing movement of the spring,- and the inner corner of the free end of said blade being shaped to cooperate with said spring to move the latte aside when said blade is shifted from open to closed position, and said blade having a hole adjacent said spring, arranged to engage an operating handle; and, an operating handle having a pin adapted to turn in the hole of said blade, and having means arranged to encounter said spring and release it from said blade when said handle is turned.

3. In an electric switch, the combination with an insulating base; of two switch terminals mounted on said base; a switch blade pivotally connected with one of said termimils and arranged to swing to and from electrical contact with the other of Said terminals; a locking spring arranged as an abutment which normally prevents its open iug movement until said spring is moved aside; said blade having its portion which engages said abutment so inclined that stresses upon said blade tending to open it presssaid inclined portion thereof against the abutment in such manner as to offer additional resistance to the releasing moveiucnt of the spring, and the inner corner of the free end of said blade being shapedto coiiporate with said spring to move the latter aside when said blade is shifted from open to closed position; and said blade having means adjacent said spring, arranged to engage an operating handlc;-and, an open ating handle having means arranged to engage said blade and means arranged to on: counter said spring and release it from said blade.

4. In an electric switch, the combination with an insulating base; or two switch terminals mounted on said base; a switch blade pivotally connected with one of said terminals and arranged to swing to and from electrical contact with the other of said terminals; a locking spring'arranged as an abutment which normally prevents its open movement until said spring is moved asi said blade having its portion which er i said abutment'so inclined that stresses up said blade tending to open. it press said inclined portion thereof against the abutmentin suchlnianner as to offer additional resistance to the releasing movement of the spring, and the inner corner of the free end of said blade being shaped to cooperate with said spring to move the latter aside when said blade is shifted from open to closed position; and, an operating handle having means arranged to engage said blade and means arranged to encounter said spring and release it from said blade.

5. In an electric switcln the combination with an insulating base; of two switch terminals mounted on said base; a switch blade pivotally connected with one of said terminals and arranged to swing to and from I electrical contact with the other of said terminals; a locking spring arranged as an abutment which normally prevents its open ing movement until said spring is moved aside; said blade being shaped to cooperate with said spring to move the latter aside when said blade is shifted from open to closcd position; and, an operating handle having means arranged to engage said blade and means arranged to encounter said spring and release it from said blade.

(3. In an electric switch the combination with an insulating base; of two switch terminals mounted on said base; a switch blade pivotally connected with one of said terminals and arranged to swing to and from electrical contact with the other of said terminals; a locking spring arranged as an abutment which normally prevents opening movement of said blade; said blade having its portion which engages said abutment so shaped that stresses upon said blade tei'iding to open it press said portion thereof. against the combination base a switch terminals mounted on sai" switch blade pivotally connected with one of said terminals and arranged to swing to and from electrical contact. with the other of said terminals; a locking spring arranged as an abutment which normally prevents opening movement of said blade; said blade having a portion which directlv engages said spring so shaped that stresses upon said blade tending to open it press said portion thereof against the spring in such manner as to olfcr additional resistance to the releasing movement of the spring, and the inner corner of the free end of said blade being shaped to cooperate with said spring to move the latter aside when said blade is shifted from open to closed position.

8. In an electric switch, thecombination with an insulating base; of two switch terminals mounted on said base; a switch blade pivotally connected with one of said terminals and arranged to swing to and from electrical contact with the other of said terminals; a locking spring arranged as an abutment which normally prevents opening movement or said blade; said blade having a portion which engages saidspring s0 shaped that stresses upon said blade tending to open it press said portion thereof against the spring in such manner as to alter additional resistance to the releasing movement of the sprin In testimony whereof, l have hereunto signed my name at Philac clphia, Pennsylvania, this fifth day of January, 1915.

vVlLL-lAltl T, PEINGLE.

Witnesses:

1. ii. Gonrnn, Jr., 

